1. Field of the Invention
The present invention relates to a power control apparatus which may be used with a digital electronic device. The present invention also relates to a processing apparatus provided with the power control apparatus. The present invention additionally relates to a power management system for a digital electronic device having the processing apparatus.
2. Description of the Related Art
In general, a digital electronic device, for example personal computer is required to be battery-driven as it is further reduced in size. In order to meet the requirement, an electronic system, which is to be driven by less electric power, has now been developed.
In order to reduce the power consumption, in particular, a significant factor in the study of the digital system is to lower its power consumption by reducing the power consumed in semiconductor devices configuring the system (physical means) as well as by designing the system to reduce the power consumed in the overall system (logical means).
The digital electronic system is configured to have a central processing unit (CPU) having its proper data processing characteristic, various input/output (I/O) controllers, and storage devices (memories, buffers, etc.).
The power management system for a digital electronic system known by the present inventor employs a concentration power management system arranged to control power supply to the CPU, the I/O controllers, and the storage devices by a single power controller.
However, the above-mentioned power management system has no capability of controlling power to be supplied to the CPU and the I/O controllers respectively. This means that the system wastes power. Further, the power management system used in the above-mentioned power management system is configured on a basic input and output system (BIOS) requiring the operating system (OS) to be module-divided into one section depending on the hardware and the other section depending on the software. This configuration does not allow for high flexibility of design. This is another disadvantage of the above-mentioned power management system.